In the past, a typical roof structure of an existing mobile home consisted of a layer of galvanized sheet metal set upon a plurality of wood truss members. Ceiling panels of a variety of types were then applied to the underside of the wood truss members creating a cavity between the trusses which generally contained insulation. The type and extent of insulation installed and the quality of construction varied with the home manufacturer and the local and national codes in effect at the time of construction. Advances in roof construction were realized by the contributions disclosed by U.S. Pat. No. 4,045,922 to Elliott and by U.S. Pat. No. 4,424,650 to Van Note. Elliot discloses a roof apparatus for mobile homes and the like which includes several discrete layers of different types of materials, including insulation materials, bonding materials and sealing materials which together provide insulation from heat and cold. Materials are selected for minimizing damage to the mobile home by flexing of the mobile home such as resulting from wind. Van Note discloses an improved roof insulation system and method for a building having a sidewall and an upper supporting surface. The insulation system includes a first substantially rigid insulation disposed about the periphery of the upper surface of the building. A second flexible insulation is disposed within the central area defined by the first rigid insulation thereby insulating the entire upper supporting surface of the building. A flexible waterproof covering is located upon the first and second insulations with the first insulation supporting the periphery of the waterproof covering and with the second insulation supporting the central area of the waterproof covering. Flashing is secured by mechanical fasteners to seal the terminal ends of the waterproof covering to the building about the periphery of the upper supporting surfaces, thereby producing a waterproof insulating roof system.
Notwithstanding the contributions of the prior art, several problems remain in the art of roof construction. The typical roof structure includes an existing metal roof which serves as a waterproofing barrier and a structural component. The insulation material may be applied between the truss members beneath the existing metal roof as previously described or above the existing metal roof and beneath the waterproof covering as disclosed by Elliott and Van Note. One problem is that the insulating material of the prior art is applied in a manner such that the insulation is subject to moisture accumulation and condensation buildup. The varying nature in the installation of insulation material may result in a transition of the temperature at which the moisture condenses into liquid, that is the dew point may shift resulting in condensation buildup in the insulation material. A second problem is that the prior art does not provide a means of escape for the moisture accumulation and condensation buildup in the insulation layer. Since the insulation material retains the condensation, the insulation value degenerates and may not regain the insulative qualities necessary to properly insulate the structure.
One method developed in the prior art to cope with these problems was the utilization of a vapor barrier in the roof structure. It was considered good insulating practice to use the vapor barrier to protect the insulating material from condensation buildup. Generally, the existing metal roof or other metal layer was utilized as the vapor barrier, however the seams of the vapor barrier continued to permit the migration of moisture and condensation and relief of vapor pressure through the vapor barrier. Thus, the moisture accumulation in the insulation material results in a third problem, the accelerated rusting of the original metal roof and subsequent structural inadequacy. The rusting of the metal roof may also cause absorption and retention of heat from solar radiation and the constant exposure to the elements causes significant thermal movement of the metal roof resulting in metal seam deterioration and expansion-contraction noise known as roof rumble. The continued thermal movement of the metal roof particularly at the roof perimeter may result in the eventual rupture of the waterproof covering at the perimeter with the loss of wind uplift resistance and failure of the roof structure. Another problem concerns the need for the reduction of stress on the sealed portions of common roof penetrations. Such stress accommodation is necessary to facilitate the occasional foot traffic on the roof and to extend the life of the roof penetration seals. Another problem concerns the rusting of the mechanical fasteners utilized as connectors in the construction of the structural roof. The rusting leads to the premature failure of the fasteners and also to rust stains on the exterior sidewalls of the mobile home, an esthetic consideration.
Thus, the problems of moisture accumulation and condensation in the insulation resulting in the loss of insulative qualities, the need for a means of escape of the moisture accumulation, the accelerated roof rusting and resultant roof leakage, heat retention and roof rumble, the lack of wind uplift resistance, stress accommodation on roof penetration seals and the rusting and failure of mechanical fasteners continue to exist and have not been solved by the prior art.
It is therefore an object of the present invention to provide an improved insulating roof system capable of retaining the insulative qualities of the insulation layer.
It is a further object to provide an improved insulating roof system capable of releasing vapor pressure through the normal mechanics of gaseous flow.
It is a further object to provide an improved insulating roof system capable of eliminating moisture vapor intrusion.
It is a further object to provide an improved insulating roof system capable of minimizing the stress on roof penetration seals from foot traffic.
It is a further object to provide an improved insulating roof system capable of securely binding the roof to the structure.